Add ForEachResource and CollectResources utils functions

[smallinsky]

What

This PR introduces the helper functionsForEachResource and CollectResources, which handle pagination automatically. These functions support the following function signatures:

• like: ListStaticHostUsers, ListOktaAssignments, ListAppSessions

  func(context.Context, int, string) ([]T, string, error)

• or like: ListPermissionSets, ListAccountAssignments with signature:

  func(context.Context, int, *pagination.PageRequestToken) ([]T, pagination.NextPageToken, error)

Why

These helper functions simplify resource collection by eliminating the need for manually handling pagination logic. Instead of writing code like this:

	var accessLists []*accesslist.AccessList
	var nextKey string
	for {
		var page []*accesslist.AccessList
		var err error
		page, nextKey, err = client.AccessListClient().ListAccessLists(ctx, 0, nextKey)
		if err != nil {
			return trace.Wrap(err)
		}

		accessLists = append(accessLists, page...)

		if nextKey == "" {
			break
		}
	}

which is prone to bugs e.g.,

• passing an incorrect nextKey to the list function
• Forgetting to update nextKey
• creating a loop scoped variables like:

  var nextKey string
  for {
   page, nextKey, err := client.ListAccessLists(ctx, 0, nextKey)
  ...
  }

users can now simply call:

accessLists err := utils.CollectResources(ctx, svc.ListAccessLists)

This approach minimizes potential errors and makes code more concise and readable.

[flyinghermit]

Nice

[flyinghermit]

nit: set default pageSize if not provided with WithPageSize ? its usually apidefaults.DefaultChunkSize value used as default.

should we also validate the pagesize provided with WithPageSize?

[smallinsky]

The 0 value is valid as page side. I it will mean that the server will use default page size and it is commonly used patter in our codebase for instance

teleport/tool/tctl/common/acl_command.go

Line 121 in fa97b8f

page, nextKey, err = client.AccessListClient().ListAccessLists(ctx, 0, nextKey)

[public-teleport-github-review-bot]

@smallinsky See the table below for backport results.

Branch	Result
branch/v17	Create PR